Various building structures for the storage of granular material have been proposed. One type of building structure which lends itself to such use, is a segmented building structure, which is generally comprised of a plurality of factory-manufactured panels which are secured together to form a dome-shaped structure which diminishes in size from bottom to top. Examples of such structures may be found in U.S. Pat. Nos. 3,820,292 to Fitzpatrick; 4,665,664 to Knight and 4,686,801 to Eriksson, et al. Such structures find wide acceptance as storage facilities for granular material due primarily to their relatively inexpensive cost compared to other type of building structures.
A problem with such structures, however is that structural limitations inherent in their designs generally limit their size and application. In this respect, the structure shown in U.S. Pat. No. 3,820,292 is essentially comprised of a plurality of wedge-shaped sectors which converge upwardly from the base of the building to a point at the top of the building. Each sector is basically comprised of a plurality of individual panels, each of which has straight side members which converge from a bottom plate member to a smaller top plate member. In other words, the sides of each panel slope inwardly from the base to form a trapezoidal shape.
While the disclosed design has proved commercial successful, its inherent design limitations basically restrict sizes of structures built thereby. In this respect, when manufacturing a structure, it is desirable to both utilize commercially available construction material, and to minimize fabrication time. To maximize use of commercial grade material, the largest panel in the structure (i.e. the lowest panel at the base of the structure) is preferably dimensioned to have a length and height which correspond to the length and width of the largest commercially available construction material. Of course, the size (diameter) of a dome structure may be increased by increasing the number of the base or bottom panels (it being understood that increasing the diameter increases the height of the resulting dome). With each additional base panel however, a new sector is created and the panels in such sector become successively smaller as they approach the upper end of the sector near the peak of the dome. It is these smaller panels located near the peak of the structure which are costly to produce in that their size does not economically utilize available construction materials.
U.S. Pat. No. 4,665,664 to Knight discloses a dome building structure comprised of convex panels. The convex panels are similar to those shown in the Fitzpatrick U.S. Pat. No. 3,820,292 in that the panels are generally trapezoidal in shape and include opposed upwardly converging side members. Unlike the panels disclosed in the Fitzpatrick patent, however, the outer edges of the top and bottom plate members are curved to form panels which are outwardly convexed from side-to-side. While these conical panels provide greater structural strength than those disclosed in the Fitzpatrick patent and thus would be preferable when building larger domes, the structure is nevertheless limited in its application for the same reasons set forth above with respect to the Fitzpatrick dome, i.e. the larger the dome, the greater the number of sectors and the larger the number of panels, (large and small alike) which must be fabricated. In addition, the fabrication of the outer edges and construction of the curved panels increases the overall cost of such structures.
U.S. Pat. No. 4,686,801 to Eriksson, et al. shows yet another dome structure comprised of a plurality of individual panels. Each panel includes an outer surface which is convexed from side-to-side. While these panels have upwardly and inwardly converging rectilinear sides, they also include an upwardly concave top plate member and a downwardly convex bottom plate member. More specifically, the top and bottom plate members have outer edges which are outwardly curved and at the same time are bowed, concavely and convexly respectively to form essentially conical surfaces. In this respect, the top and bottom plate members of the panels forming a given ring thus define annular conical surfaces. Importantly, these mating conical surfaces permit panels above and below to be offset, wherein joining lines formed by adjacent panels can be staggered from one ring to another to strengthen the resulting structure. A major drawback of the disclosed structure, however, is the fabrication cost involved in producing such panels. As will be appreciated, the cost of producing such concave/convex curved panels is substantially greater than the cost of producing a flat panel.
The present invention overcomes the foregoing limitations inherently found in dome structures known heretofore and provides a building structure which effectively utilizes the cost efficiency of flat panels, but which reduces the number of small panels required near the peak of such structures.